ng_ipfw
—
interface between netgraph and IP firewall
The ipfw
node supports an arbitrary number
of hooks, which must be named using only numeric characters.
Once the ng_ipfw
module is loaded into the
kernel, a single node named ipfw is automatically
created. No more ipfw
nodes can be created. Once
destroyed, the only way to recreate the node is to reload the
ng_ipfw
module.
Packets can be injected into
netgraph(4)
using either the netgraph
or
ngtee
commands of the
ipfw(8)
utility. These commands require a numeric cookie to be supplied as an
argument. Packets are sent out of the hook whose name equals the cookie
value. If no hook matches, packets are discarded. Packets injected via the
netgraph
command are tagged with
struct ipfw_rule_ref. This tag contains information
that helps the packet to re-enter
ipfw(4)
processing, should the packet come back from
netgraph(4)
to
ipfw(4).
Packets received by a node from
netgraph(4)
subsystem must be tagged with struct ipfw_rule_ref
tag. Packets re-enter IP firewall processing at the next rule. If no tag is
supplied, packets are discarded.
This node type supports only the generic control messages.
This node shuts down upon receipt of a
NGM_SHUTDOWN
control message. Do not do this, since
the new ipfw
node can only be created by reloading
the ng_ipfw
module.
The ipfw
node type was implemented in
FreeBSD 6.0.